Overcurrent relay having contacts mounted independently of its armature



Oct. 20, 1964 F. P. SPINELLI ETAL 3,153,712

OVERCURRENT RELAY HAVING CONTACTS MOUNTED INDEPENDENTLY OF ITS ARMATURE 3 Sheets-Sheet 1 Filed Nov. 3, 1960 INVENTORS:

6. JU/VGHA NS FRANK P .SP/NELL/ 5 m Q a m M mm H m m 5 7m 7 w 4 %7 4 TOQNEY 1964 F. P. SPINELLI ETAL 3,

OVERCURRENT RELAY HAVING CONTACTS MOUNTED lNDEPENDENTLY OF ITS ARMATURE Filed Nov. 3. 1960 3 Sheets-Sheet 2 i Z 48 b9 71 9 1 INVENTORS: FRANK f? SP/NZL/ B FAGDt-R 5. Juuanmvs AZOFNE) 06L 20, 1964 F. P. SPINELLI ETAL 3,153,712

OVERCURRENT RELAY HAVING CONTACTS MOUNTED INDEPENDENTLY OF ITS ARMATURE Filed Nov. 3. 1960 3 Sheets-Sheet 3 Tiiilxx. T121115- Ticzlllc.

IN V EN TORS I 37 52mm F sl m/ELL I FkEDR/ 5. June HANS ,q river/Ev United States Patent 3,153,712 UVERCURRENT RELAY HAVHNG CQN- TACTS MGUNTED INDEPENDENTLY OF ITS ARMATURE Frank I. Spinelii, Teaneclr, and Frederic B. Junghans, Netcong, N..li., assignors to Automatic Switch Co., Florhani Paris, Nh, a corporation of New York Filed Nov. 3, 19st, Ser. No. 67,085 11 Claims. (ill. 2tlll-lll) This invention relates to relays, and more particularly to relays of the type which are responsive to excessive current in a circuit being monitored to perform a preselected function.

Overcurrent relays of the type to which the present invention relates are arranged in series connection with a load circuit so that they monitor the current values in the circuit. When the current rises above a predetermined value, the relay becomes energized and operates one or more contacts forming part of an auxiliary circuit. The auxiliary circuit may be, for example, a control circuit which includes the coil of a contactor Whose contacts are arranged in the load circuit. In such a case, when the overcurrent relay is energized by an excessive current in the load circuit, it will cause actuation of the contactor which will in turn deenergize the load circuit.

Since these relays are placed in series in the load circuit, it is important, if they are to provide adequate protection, that they have low inductance and resistance so that they do not interfere with the regulation of the power supply to the load circuit.

It is therefore a general object of the invention to provide an overcurrent relay having low inductance and low resistance. It is a further object to provide such a relay having a time response inversely proportional to the current load through the relay coil, i.e., the higher the current applied to the coil, the shorter the time of relay operation.

in conventional relays having normally closed contacts, the contacts are mounted to move with the armature of the relay and are spring biased toward closed condition. Since the contacts have the effect of loading the armature, the response of the latter tends to be erratic, unless the contact biasing springs are adjusted critically. It is therefore an important object of this invention to provide an overcurrent relay in which the relay contacts are mounted independently of the armature and arranged to be actuated by the armature only after movement of the latter has been initiated. In this way, the armature may be loaded solely by an axially mounted biasing spring whose adjustment controls the response of the armature to any chosen current through the relay coil. Response is thus rapid and accurately controllable.

it is another object of the invention to provide means for readily and precisely adjusting the contact pressure of the independently mounted contacts.

Overcurrent relays are sometimes employed in great numbers in a single installation, such as in a computer, wherein they are arranged close together in a bank. Consequently, when one of the relays is tripped, it may be difiicult for an attendant quickly to locate it unless the relay is adapted to signal the fact that it has been energized. It is therefore still another object of this invention to provide an overcurrent relay having a novel means for indicating that the relay has been energized.

It is yet another object of the invention to provide an overcurrent relay which is unusually, compact and so designed, structurally, that it may be mounted in close array with others with only sliding fit or clearance between adjacent relays.

It is another object of the invention to provide a relay which is capable of operating reliably for long periods of EJ53312- Patented Oct. 20, 1964 ice time without maintenance, and which is thoroughly practical in every respect.

Qther objects and advantages of the present invention will be apparent from the following description, which is made in reference to the accompanying drawings.

in the drawings:

FIG. 1 is a perspective view of an embodiment of the present invention in deenergized condition;

FIG. 2 is a view similar to FIG. 1 in which the relay is in energized condition;

FIG. 3 is a vertical cross-sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a vertical cross-sectional view taken along the line 4i of FIG. 3;

PEG. 5 is a rear elevational view of the relay;

FIG. 6 is a fragmentary perspective view showing the relay latching means;

FIG. 7 is an enlarged fragmentary cross-sectional view showing the relay armature and contacts in deenergized condition;

FIG. 8 is a view similar to FIG. 7 showing the relay armature and contacts in energized condition;

PEG. 9 is a perspective view, partially in cross-section, showing the coil of the present relay;

FIG. 10 is a diagrammatic circuit arrangement showing one way in which the present relay may be employed;

FIGS. ll-a, llb, and show an alternative embodiment of the present invention in which the relay armature is adapted to automatically reset itself upon being deenergized but the signal must be manually reset; and

FIGS. 12a, 12b and show another alternative embodiment in which both the relay armature and signal automatically reset themselves.

In the embodiment of the invention illustrated in FIGS. l9, the relay is provided with a frame assembly 15 comprising a front plate 16 and four studs (two long studs 1'7 and two short studs 13) threaded into the plate 15 and projecting perpendicularly therefrom. The studs 17 and 18 are disposed in a rectangular arrangement, the studs of each pair being diagonally opposed to one another, and support an insulated bobbin upon which the relay coil is wound. The bobbin is formed by two rectanguilar end sections 19 joined by an insulated tube 20 (see FIG. 7) having a circular cross-section. Fixed inside the tube 29 is a metallic tube 21 (preferably of copper) equal in length to the length of the bobbin. The end sections 19 are provided with aligned apertures in each of their corners through which the studs 17 and 18 pass. A plate 22 is arranged between one end section of the bobbin and the front plate 16, and a bearing plate 25 and flux plate 26 are located adjacent to the outer face of the opposite end section 19. Each of the plates 22, 25 and 26 is provided with a rectangular pattern of apertures for accommodating the studs 17 and 18. The short studs 13 terminate a short distance beyond the flux plate 26, and their free ends are threaded to accept nuts 27. The longer studs 17 extend past the short studs 18 and through a pair of apertures in a terminal block 28. The long studs each carry a spacer 29 for supporting the terminal block 28 at a fixed distance from the front plate 16. The free ends of the studs 17 are threaded to accept the nuts 36 which serve to lock the terminal block in place, and to secure a spring seat member 31 to the outer face of the terminal block. An insulating washer 32 is arranged between the terminal block and the spring seat member. An insulated dust cover 35 slides over the edges of the front plate 16 and the terminal block 28, and is held in place by a screw 36 threaded through the dust cover and into the terminal block. The dust cover 35 serves to enclose the relay coil and the relay contacts.

The dust cover, and the elements 16 and 28, are substantially rectangular so that the resultant unit is a compact one having planar side faces whereby a multiplicity of such units can be readily assembled in close juxtaposition, side by side, row upon row, within a relatively confined space. For computer use, this is an important advantage.

The coil 37 of the relay is wound about the tube 20, and extends between the end sections 19 of the bobbin. In the preferred embodiment of the invention, the winding 37 consists of a thin fiat copper strip 38 wound continuously and concentrically around the tube 20. Adjacent layers of the winding are separated from one another by a strip insulating material 43 wound continuously with the strip 38. The width of the strip 33 is slightly less than the distance between the end sections 19 so that the edges of the strip are spaced from the end sections (see FIGS. 7 and 8). The insulation material 4-3, however, is equal in width to the distance between the end sections 19 and therefore the insulation extends past the edges of the strip 38. It will be appreciated that the type of winding just described presents only one turn per layer, and thus the inductance of such a winding is reduced substantially over conventional coils. In addition, the separation of the layers is a minimum represented by the thickness of the strip 38 plus the thickness of the interlayer insulation. The advantage of this type of winding may be seen from the following example: A nominal ampere rated relay will use .006 inch thickness of copper strip plus .002 inch thickness of interlayer insulating material. Tests have shown that such a winding has one-half the inductance of an equivalent conventional winding. A further advantage of this type of winding is the high space factor achieved resulting in minimum resistance and maximum heat dissipation ability.

In addition the combination of the inner copper tube 21 and the copper strip 38 winding results in an inverse time response curve as a function of current. As is well known, eddy currents in a magnetic circuit tend to oppose the rise of magnetic flux resulting from current flow. Eddy currents are induced in the combination described, and since these eddy currents act to oppose the build up of the normal flux, the relay will operate with a variable delay as a function of the current. For example, in a relay of this type, it was found that the operating time at 600% of rated current was one-half the time at 300% of rated current, and one-third of the time at 200% of rated current.

The ends of the winding 38 are soldered to straps 39 which are fastened to suitable binding posts 40 carried by the terminal block 28. The binding posts are threaded to receive lock washers and nuts 41 for securing the end of a conductor to the binding post.

The terminal block 28 carries another pair of binding posts 42, each of which is provided with a soldering lug 45. At its center the terminal block 28 is provided with a circular aperture lined by a metallic contact ring 46. The outer end of the contact ring 46 is separated from the spring seat member 31 by the insulating washer 32, while the inner end of the contact ring extends a short distance beyond the inner face of the terminal block 28. (See FIGS. 7 and 8.)

Mounted on the inner end of each of the binding posts 42 is a relay contact assembly. This assembly includes a relatively rigid lever 47 fastened at one end to the binding post 42. At its free end, the lever 47 is provided with a threaded aperture which accommodates a set screw 4-8. A leaf spring 4-9 is riveted at one end to an intermediate point on the lever 47, and extends over the edge of the contact ring 46. Directly over the edge of the contact ring, the leaf spring 49 carries a contact 50 which normally engages the edge of the contact ring as shown in FIG. 7. The free end of the leaf spring is formed with an abutment surface 51. Normally, therefore, the circuit into which the binding posts as are connected will be completed through one of the contacts 50, the contact ring 46, and the other of the contacts 50.

It will be seen that the contact pressure of the contacts 50' on the contact ring 4-6 may be varied by means of the set screws 43. The ends of the set screws bear against the inner face of the terminal block 23. Therefore, as one of the set screws is rotated in one direction the free end of its associated lever 47 will move away from the terminal block and cause the leaf spring 4) mounted on it to be flexed, thereby increasing the pressure of the contact 50 against the contact ring 46. If the set screw is rotated in the opposite direction, the contact pressure will be reduced.

The armature 52 of the relay is axially arranged within the metallic tube 21. Projecting axially from the front end of the armature 52 is a stem 55, and projecting axially from the rear end of the armature is a threaded extension as. The armature is supported in a low friction bearing 57 carried by the bearing plate 25, and the stem 55 is supported in a low friction bearing 53 carried by the front plate 16. Threaded onto the extension 56 are a pair of identical but oppositely arranged bushings 5d and Q50. The bushing 59 is adapted to engage the spring seat member 31 through the insulating washer 32 and thus fix the normal position of the armature 52 (FIG. 7). The armature is urged into and maintained in its normal position by a biasing spring 61 which surrounds the extension 56 between the spring seat 31 and a cup Washer 62 carried by the extension. A nut e5 locks the cup washer on the extension 56-. A cylindrically-shaped guard 66 encloses the free end of the extension 5 5 and is crimped near its inner end to form a locking relationship with the reduced diameter region 67 of the spring seat member 31.

The bushing 60 is arranged out of engagement with the leaf springs 49 when the armature 52 is in its normal position. However, when the armature moves to its energized position (FIG. 8), the bushing 60 engages the abutment surfaces 51 of the leaf springs 49 and flexes them, thus lifting the contacts 50 off the contact ring 46.

Mounted on the outer face of the front plate 16 by means of screws 68 is a shield 6 The central region of the shield 69 is spaced from the front plate 16, and is provided with two apertures 70 and 'ill. The body of a stationary indicator 72 is arranged between the shield 69 and the front plate 36, and a reduced diameter portion of the indicator 72 projects forwardly through the aperture 70 in the shield. Preferably, the indicator is brightly colored, and may be formed, for example, of plastic.

As may be seen in FIG. 6, the aperture 71 is formed by a vertical slot, a horizontal slot bisecting the vertical slot and being itself bisected by the vertical slot, the horizontal slot being slightly shorter than the vertical slot, and two opposed arcuate regions each of whose radius equals one-half the length of the horizontal slot. The stem 55 carried by the armature 52 passes through the aperture '71, and carries a latch member 75. The latch member is rotatable on the stem 55, and presents a key, having a rectangular cross-section, for engagement with the aperture '71. A reduced region 76 of the key is about equal in size to the horizontal slot forming part of the aperture 7t, and a larger region '77 is about equal in size to the vertical slot. When the armature 52 is in normal position, the region '77 is disposed in the vertical slot of the aperture '71 thus preventing rotation of the latch member 75.

Fixed to the latch member 75 is an arm 78 which carries a C-shaped bracket 79. The bracket '79 is provided with an aperture through which the stem 55 passes. The free end of the stem is threaded to accommodate a pair of nuts 80 disposed on opposite sides of the bracket 79. The nuts 80 serve to prevent any appreciable axial movement of the latch member 75 with respect to the stem but are spaced far enough apart to permit rotary movement of the latch member. At its upper end the arm 78 carries a weight 81 mounted eccentrically with respect to the stem 55.

When the relay is energized, the armature 52 moves leftwardly (as depicted in the drawings) until its front end strikes the inner face of the front plate 16 (FIG. 8). In this position, the region 77 of the latch member 75 moves out of the aperture '71 and permits the eccentrically-mounted Weight 81 to rotate the arm 78 from the position shown in FIG. 1 to the position shown in FIG. 2. While the indicator 72 is concealed when the arm '78 is in its vertical position, the indicator is revealed when the arm swings down to its horizontal position, thus permitting an attendant to determine readily that the relay has been tripped. Inasmuch as the region 77 of the latch is longer than the horizontal slot forming part of the aperture 71 in the shield 69, this region bears against the outer face of the shield 69 and prevents the armature 52 from returning to its normal position even after the excessive current flow through the coil has been remedied. In order to reset the armature, the attendant must swing the arm 78 back to the position shown in FIG. 1, at which point the spring 61 will pull the key portion of the latch back through the aperture 71 and return the armature to its normal position, As the armature is thus reset, the indicator 72 is once again concealed. In this embodiment of the invention, therefore, both the armature and the indicator are manually reset.

FIGS. 11a, 11b and 110, and 12a, 12b and 12c show alternative embodiments of the invention, in which the armature of the relay is automatically reset when the condition of excessive current is remedied.

In FIGS. 11a, 11b and 110, the armature 52a of the relay is provided with a stem 55a similar to but somewhat shorter than the stem 55. Fitted over the stern 55a is a tubular member 82 slidable with respect to the stem 55a. Integral with the member 82 is an indicator button 83 located in an aperture in the shield 69a, the aperture being provided with a felt gasket 93. In normal position, the outer face of the indicator 83, which may be the same color as the shield 69a, is flush with the outer face of the shield (FIG. 11a). When the armature is energized, the stem 55a pushes the indicator S3 outwardly (see FIG. 11b) thus exposing its edges as, which are preferably brightly colored. The indicator 83 is provided with a flange 92 for limiting its outward movement, When the relay is viewed at an angle, therefore, the colored edges 86 of the indicator will be visible. When the excessive current condition in the coil is remedied, the armature 52a will return to its normal position (FIG. 110) under the influence of a spring similar to the spring 61. However, since the member 82 is slidable with respect to the stern 55a, the indicator 83 will remain in its protruding condition. In order to return the indicator $3 to its normal position, the attendant merely pushes it inwardly until it is flush with the shield 69a. It will be seen therefore, that the embodiment of the invention shown in FIG. 11 provides automatic reset of the relay armature, but manual reset of the indicator.

In FIGS. 12a, 12b and 120, the armature 52b is provided with a stem 55b similar to the stem 55a. The stem 55b is arranged to pass through an opening in the shield 69b. Directly above this opening, the shield is provided with a pair of ears 87 which support a rod 88. Swingably mounted on the rod 38 is an indicator arm 89 whose lower end is turned 90 to the remainder of the arm 89. The lower face 90 is preferably brightly colored. When the armature 52b is in normal position, as in FiG. 12a, the colored face 90 will not be visible. However, when the armature 52b is energized, the stem 55b will strike the rear face of the indicator arm 89 and swing the latter upwardly until the brightly colored face 90 is in an almost vertical plane (FIG. 12b). When the armature is once again deenergized, it will return to its normal position and the indicator arm 89 will be permitted to swing downwardly into its normal position. It may be seen, therefore, that in the embodiment shownin FIGS. 12a, 12b and 120, both the relay armature and the indicator automatically reset themselves.

Referring now to FIG. it), the diagram indicates one Way in which an overcurrent relay of the present type may be employed. A load circuit is shown including a load and two normally open contacts C-2 and 0-3 of a contactor connected across a source of DC. power. Arranged in series with this load circuit is the coil 37 of the present relay. This connection can be made by securing the conductors of the load circuit to the binding posts of the relay. An auxiliary control circuit is also provided including the coil C of a contactor, the normally open contacts (3-1 of the contactor, the normally closed stop push button, and the normally open start push button connected in parallel across the contacts C-l. Connected in series with this control circuit are the contacts 50 and the contact ring in of the relay. This connection may be made by securing the conductors of the control circuit to the binding posts 42 of the relay.

When the start push button is depressed, a circuit is completed through the contactor coil C, the contacts 50 and contact ring to, the start push button, and the stop push button, thus energizing the contactor coil C. As a result, the contacts C2 and C4: close to energize the load, and the contacts C-l close to make the control circuit self-holding. As long as the current in the load circuit remains normal, the load circuit will remain uninterrupted. However, when the current through the load circuit reaches a trip value, the coil 37 will be energized and will move the armature 52 thus lifting the contacts 58 off the contact ring 46. The control circuit will thereby be broken and the contactor coil C will be deenergized. Consequently, the contacts C2 and (3-3 will open, deenergizing the load.

If the relay is of the automatic reset type, it will be seen that the control circuit can be reenergized merely by once again depressing the start push button. However, if the relay is of the manually reset type, then the armature must be unlatched first before the control circuit can be reenergized by means of the start push button.

In many respects, of course, the details herein described may be modified by those skilled in the art without necessarily departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. For use in an electrical installation to be protected against flow of excessive current, said installation including a load circuit and a control circuit for interrupting the load circuit when current in excess of a predetermined value is present: an overcurrent relay comprising a frame, a coil mounted on said frame and arranged in series connection with said load circuit, an armature within said coil and adapted to move longitudinally when the current through said coil reaches a predetermined value, a make and break switch carried by said frame, said make and break switch including a movable contact unconnected to said armature, said movable contact being located adjacent to the path of movement of said armature, means carried by said armature and adjustable longitudinally thereof for engaging and moving said contacts when the current in said coil reaches said predetermined value, an arm rotatably mounted on one end of said armature, and a latch rotatably mounted on said armature and fastened to said arm, said latch normally engaging said frame to maintain said arm in one position, said armature being effective upon moving longitudinally to release said latch and permit said arm to move to another position.

2. An overcurrent relay comprising a frame, a coil mounted on said frame, an armature within said coil and adapted to move longitudinally when the current through said coil reaches a predetermined value, an abutment member carried by said armature, and a make and break switch including at least two spring contacts mounted on said frame in the path of travel of said abutment member and a metallic ring coaxial with said armature mounted on said frame and engageable by said contacts, said abutment member engaging and moving both of said contacts 7 simultaneously with respect to said ring when the current through said coil reaches said predetermined value.

3. An overcurrent relay according to claim 2 including means for adjusing the contacts pressure of said contact on said metallic ring.

4. An overcurrent relay according to claim 3 wherein each adjustment means comprises a lever upon which said contact is mounted, said lever being mounted at one end on said frame, and means for varying the distance of the other end of said lever from said frame.

5. An overcurrent relay according to claim 4 wherein said distance varying means is a screw threaded into said lever, the end of said screw bearing against said frame.

6. An overcurrent relay comprising a frame, a coil mounted on said frame, an armature within said coil and adapted to move longitudinally when the current through said coil reaches a predetermined value, a make and break switch carried by said frame and including a movable contact adjacent to the path of movement of said armature, means carried by said armature for engaging and moving said contact when the current in said coil reaches said predetermined value, an indicator carried by said frame, an arm rotatably mounted on said armature and normally positioned to conceal said indicator, and a latch carried by said armature normally engaging said frame to prevent rotation of said arm with respect to said frame, said latch being movable out of engagement with said frame to permit rotation of said arm.

7. An overcurrent relay according to claim 6 wherein said armature is adapted upon movement to simultaneously (1) engage and move said contact with respect to said frame in order to operate said make and break switch, and (2) move said latch out of engagement with said frame to permit rotation of said arm.

8. An overcurrent relay according to claim 7 including a weight eccentrically mounted on said arm, said weight upon movement of said latch out of engagement with said frame causing said arm to rotate to a second position wherein it fails to conceal said indicator.

9. An overcurrent relay according to claim 8 wherein said latch is retained by said armature out of engagement with said frame as long as the current in said coil is at least said predetermined value.

10. An overcurrent relay according to claim 8 including another latch engageable with said frame to maintain said armature in its energized condition upon the movement of said arm to its second position.

11. An overcurrent relay according to claim 10 wherein said latch for preventing rotation of said arm and said latch for maintaining said armature in its energized condition are portions of a single member carried by said armature.

References Cited by the Examiner UNITED STATES PATENTS 448,166 3/91 Sweet 200-109 1,140,491 5/15 Anderson 200-111 1,141,119 6/15 Kaisling 200109 1,312,522 8/19 Dick 200111 2,516,362 7/50 Bauer 200153 2,528,345 10/50 De Champs 200153 2,714,141 7/55 Urey et al 20087 2,749,403 6/56 Horman et al 200111 2,852,637 9/58 Pratt 20087 2,927,291 3/60 Ruehle 336223 FOREIGN PATENTS 3,825 8/ 13 Great Britain.

BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, Examiner. 

2. AN OVERCURRENT RELAY COMPRISING A FRAME, A COIL MOUNTED ON SAID FRAME, AN ARMATURE WITHIN SAID COIL AND ADAPTED TO MOVE LONGITUDINALLY WHEN THE CURRENT THROUGH SAID COIL REACHES A PREDETERMINED VALUE, AN ABUTMENT MEMBER CARRIED BY SAID ARMATURE, AND A MAKE AND BREAK SWITCH INCLUDING AT LEAST TWO SPRING CONTACTS MOUNTED ON SAID FRAME IN THE PATH OF TRAVEL OF SAID ABUTMENT MEMBER AND A METALLIC RING COAXIAL WITH SAID ARMATURE MOUNTED ON SAID FRAME AND ENGAGEABLE BY SAID CONTACTS, SAID ABUT- 